Many materials are known to be porous, generally being inherently porous. The naturally porous materials can be provided as filters or as transpiration coolers for various applications. Nevertheless, many natural materials include a porosity that is also substantially “natural”. Simply, the natural porosity of many materials is highly variable. Although porosity for various materials may be within a generally known range, the porosity can be unevenly distributed throughout the material. Moreover, the natural porosity of a selected material may be within a large range rather than within a narrow porosity range. Furthermore, a material having a selected porosity may not include other selected or desirable characteristics, such as strength.
Nevertheless, it is desirable to provide materials that include a selected porosity, and more specifically a porosity that is substantially consistent throughout the material such that natural variations do not occur within the material. Therefore, the porosity will include a selected porosity and pore size. The entire material should have a known physical characteristic and capable of being applied in a substantially consistent manner.
Moreover, most often porous materials include a substantially multi-directional porosity. That is, the porosity is distributed such that flowable materials may move through the pores in both directions, from a first side to a second side and from the second side to the first side of the material. If the porous material is provided as a filter or membrane, a pressure differential across the membrane must be relied upon to move the material in a selected direction. Generally, this requires including additional manufacturing steps or structural elements in the final structure or device.
Therefore, it is also desirable to provide a material that is substantially directionally porous. Simply, a material that includes a porosity that allows material to flow in only one direction relative to the porous material. With a pressure differential supplied across the membrane, the pores of the membrane would allow a flow of material in only one direction. The flow may be dependent upon the material in which the pores are made or the material being flowed across the membrane; nevertheless, the membrane may be substantially uni-directional in its porosity for selected flowable materials.
It is also desired to provide many materials including selected porosities. That is, materials of various types including a selected porosity that include both a selected pore density, selected pore size, and selected directional porosity. Therefore, rather than providing only a single material including a selected porosity with a general technique, the materials could be varied and used in many different applications including different strengths and weight requirements that may be provided by various materials.
Also, it is known to cool various components, such as components of a rocket engine including turbine parts, combustion chambers, and nozzles. Cooling these systems in particularly harsh environments can be difficult due to the high heat flux, strength, and heat resistance needed of the various cooling components. Therefore, providing a cooling system in such an environment is often difficult, heavy, complex, or expensive. In addition, the cooling systems are generally large and bulky due to the requirements for heat transfer and strength in the environment. Therefore, it is also desirable to provide a cooling system that can easily cool a component in a harsh environment without great size or complexity.